JP3706395B2

JP3706395B2 - Exhaust gas treatment equipment

Info

Publication number: JP3706395B2
Application number: JP06451094A
Authority: JP
Inventors: 芳雄小川; 道弘吉田; 順一古川; 博美腰塚
Original assignee: Chiyoda Corp
Current assignee: Chiyoda Corp
Priority date: 1994-03-08
Filing date: 1994-03-08
Publication date: 2005-10-12
Anticipated expiration: 2020-10-12
Also published as: JPH07241428A

Description

【０００１】
【産業上の利用分野】
本発明は、気体と液体（スラリー液を含む）とを接触させる排ガス処理装置、特に排煙脱硫装置に関するものである。
【０００２】
【従来の技術】
大型液槽内に液体を収容させ、その液体内に下部周壁面に複数のガス噴出孔を有するガス導入管（スパージャーパイプ）の多数を垂設し、そのガス導入管内に導入させたガスをガス噴出孔から液体中に噴出させて気液接触を行わせる装置は広く知られている（特公昭５５−３７２９５号、特公昭５７−６３７５号、特公昭５９−１１３２２号等）。
【０００３】
図４に、排煙脱硫装置として用いられている排ガス処理装置の模式図を示す。
図４において、ＳＯ₂を含む排煙は、導管１０１からガス導入管１０３を通り、そのガス導入管１０３の下部周壁面に設けたガス噴出口から炭酸カルシウムや水酸化カルシウム等のカルシウム化合物のスラリー液中に噴出される。この場合のガス導入管１０３は、図５に示すように、その下部周壁面に配設されたガス噴出孔１０４を有する。液槽内のカルシウム化合物のスラリー液中に噴出された排煙は、そのスラリー液と接触し、排煙中に含まれるＳＯ₂が液中に吸収されると同時に液槽下部の空気導入管１０６から液中に導入された空気中の酸素により酸化され、カルシウム化合物と反応してＣａＳＯ₄・２Ｈ₂Ｏ（石こう）になる。なお、１１２はガスに同伴された液体を捕捉する気液分離器を示し、１０５は攪拌羽根を示し、１０８は石こうスラリー抜出管を示す。
図４に示した排煙脱硫装置は、実際には極めて大型の装置であり、その液槽１０２の内径は１０ｍ以上もあり、また、そのガス導入管１０３の数も１，０００本以上という極めて多い数である。
【０００４】
このような排ガス処理装置における１つの問題点は、装置を小型化するために所定の装置におけるガス処理量を増加すると、ガス導入管に配設するガス噴出孔の全開孔面積に限界があるため、ガスの圧力損失が急激に増加することである。ガス導入管を通して液中に導入されるガス流量は、そのガス噴出孔の全開孔面積に依存し、ガス噴出孔の全開孔面積が増加するに従ってその量は増加し、単位時間当りのガス処理量を増加することができる。しかしながら、この場合には、多量のガスをガス噴出孔から液中に噴出させることから、このことが原因となって、条件によっては液面が不安定になり、液面の変動幅が大きくなり、気液接触効率悪化の原因となったりする。
【０００５】
【発明が解決しようとする課題】
本発明は、下部周壁面に複数のガス噴出孔を有するガス導入管を多数吸収液中に垂設した構造の排ガス処理装置において、増加されたガス噴出孔の全開孔面積を有しながら、液槽内の液面の変動幅が小さい、ガス処理性能に著しくすぐれた装置を提供することをその課題とする。
【０００６】
【課題を解決するための手段】
本発明者らは、前記課題を解決すべく鋭意研究を重ねた結果、本発明を完成するに至った。
即ち、本発明によれば、液槽内に収容させた吸収液中に、排ガスを、下端開口しかつ下部周壁面にガス噴出孔を有するガス導入管の多数を介して導入分散させる構造を有する排ガス処理装置において、該ガス導入管の下端開口とガス噴出孔との面積比が１：０．１〜２でガス導入管の下端とガス噴出孔の最下位との間の距離がガス導入管の内径の１〜８倍の範囲にあり、かつ直径１０〜３０ｍｍのガス噴出孔がガス導入管の周壁面に複数段に横方向に配設され、かつガス噴出孔の配設段数とガス噴出孔直径との関係が、式、
２≦ｎ≦８０／Ｄ
（式中、ｎはガス噴出孔の配設段数を示し、Ｄはガス噴出孔の直径を示す）
を満足することを特徴とする排ガス処理装置が提供される。
【０００７】
次に、本発明を図面を参照して説明する。
図１は、吸収液中に垂設したガス導入管を介して排ガスをガス導入管の噴出孔から吸収液中に噴出させる際の説明状態図を示す。この図において、１はガス導入管、２（１）、２（２）はガス噴出孔、３はフロス層、４はフロス層上面、５はガス導入管内における吸収液面、６はガス導入管の下端を示す。
排ガスは、ガス導入管１の内部を下方に流通し、ガス導入管１の下部周壁面に配設されたガス噴出孔２（１）、２（２）から吸収液中に噴出される。ガス噴出孔２（１）、２（２）から吸収液中に噴出された排ガスは微細気泡となって上昇し、ガス噴出孔より上方には気液混合物からなるフロス層３が形成される。排ガスの微細気泡は、このフロス層内を上方に移動する間に吸収液と接触し、排ガス中の汚染物質は吸収液と反応し、除去される。
【０００８】
前記のようにして排ガスと吸収液との接触を行わせる場合、ガス導入管１の内圧を上昇させずに単位時間当たりの排ガス量を高め、これにより装置の小型化を達成しようとすると、ガス導入管の噴出孔の直径を大きくして多量のガスを吸収液中に導入分散させる必要性がある。本発明者らの研究によれば、図５に示すように、周壁面に横一列に配設されている従来のガス導入管においてガス噴出孔の直径を増加させてガス噴出量を高める場合、ガス噴出量は増加するものの、ガス噴出孔の直径が４０ｍｍを超えるようになると、吸収液面の変動幅が著しくなり、気液接触効率が大きく低下することが判明した。
図２に、前記のようにして排ガスを吸収液中に噴出させる場合のガス空塔速度（ｍ／秒）とガス噴出孔の直径との関係及び吸収液面の変動幅とガス噴出孔の直径との関係を示す。この場合、ガス空塔速度はガス導入管１から噴出した排ガスがフロス層３を通過し上方に移動する際のガス空塔速度を示し、吸収液面の変動幅は、ガス導入管１内の吸収液面５が上下に変動する場合のその液面の最下位と最上位との間の距離を示す。
図２からわかるように、横一列に配設した噴出孔の場合には、その噴出孔の直径に制限を受け、ガス流量を大幅に増加させることは困難である。
【０００９】
そこで本発明者らは、ガス噴出孔の配列を複数列に配設することを検討した結果、図３に示す結果が得られることを見出した。
即ち、図３からわかるように、噴出孔（直径１０ｍｍ）の配列段数が増加するにつれてガス空塔速度も増加するが、その噴出孔配列段数が８段を超すようになると液面の変動幅が大きくなり、１０段以上になると液面変動幅が大きくなる。
【００１０】
図３の関係は一定の条件下で得られたもので、本発明の場合、以下の条件を満足する必要がある。
（１）噴出孔の直径Ｄが、１０〜３０ｍｍ、好ましくは１５〜２５ｍｍの範囲であること。
（２）ガス導入管の直径Ｒが５０〜３００ｍｍであること。
（３）ガス導入管の下端開口面積（ガス導入管の断面積）とガス噴出孔面積との面積比が、１：０．２〜２であること。
（４）ガス導入管の下端から最下段の噴出孔の最下位までの距離Ｌ（図１参照）が、ガス導入管の内径Ｒの１〜８倍であること。
（５）ガス噴出孔の直径Ｄとガス噴出孔の配列段数ｎとの関係が、以下の式を満足すること。
２≦ｎ≦８０／Ｄ
（式中、ｎはガス噴出孔の配列段数を示し、Ｄはガス噴出孔の直径（ｍｍ）を示す）
【００１１】
【発明の効果】
本発明の排ガス処理装置は、ガス導入管の内圧を格別上昇させることなく、ガス噴出孔の配列段数のみを一定条件下で増加させることにより、吸収液中へのガス導入分散量を増加させ、装置の単位時間当りのガス処理量を向上させることができる。従って、一定のガス量を処理するときには、本発明の装置は、従来の装置に比べて大幅に小型化させることができる。
本発明の排ガス処理装置は、各種の気液接触を伴う排ガス処理装置として利用され、例えば、亜硫酸ガスを含む排ガスと炭酸カルシウムスラリー液等のアルカリ性液体からなる吸収液との接触を行う排煙脱硫装置や、炭酸ガスを含む排ガスとアルカリ性液体からなる吸収液との接触を行う脱炭酸ガス装置等として好ましく適用される。特に、本発明の装置は、液槽の直径が１０ｍ以上、特に２０ｍ以上という大型の排煙脱硫装置として有利に用いることができる。
【図面の簡単な説明】
【図１】吸収液中に垂設したガス導入管を介して排ガスをそのガス噴出孔から吸収液中に噴出させる際の説明状態図を示す。
【図２】ガス空塔速度とガス噴出孔の直径との関係及び吸収液面の変動幅とガス噴出孔の直径との関係を示す。
【図３】ガス空塔速度とガス噴出孔の配列段数との関係及び吸収液面の変動幅とガス噴出孔の配列段数との関係を示す。
【図４】非煙脱硫装置として用いられている従来の排ガス処理装置の模式図を示す。
【図５】ガス導入管の構造説明図を示す。
【符号の説明】
１、１０３ガス導入管
２（１）、２（２）、１０４ガス噴出孔
３フロス層
４フロス層上面
１０１ガス導管
１０２液槽
１０５攪拌羽根
１０６空気導入管
１０８石こうスラリー抜出管[0001]
[Industrial application fields]
The present invention relates to an exhaust gas treatment apparatus that brings gas and liquid (including slurry liquid) into contact with each other, and particularly to an exhaust gas desulfurization apparatus.
[0002]
[Prior art]
A large liquid tank contains liquid, and a number of gas introduction pipes (sparger pipes) having a plurality of gas ejection holes on the lower peripheral wall surface are suspended in the liquid, and the gas introduced into the gas introduction pipe Apparatuses that make gas-liquid contact by ejecting into a liquid from gas ejection holes are widely known (Japanese Patent Publication No. 55-37295, Japanese Examined Publication No. 57-6375, Japanese Examined Publication No. 59-11322, etc.).
[0003]
In FIG. 4, the schematic diagram of the waste gas processing apparatus used as a flue gas desulfurization apparatus is shown.
In FIG. 4, flue gas containing SO ₂ passes through a gas introduction pipe 103 from a conduit 101 and is a slurry of a calcium compound such as calcium carbonate or calcium hydroxide from a gas outlet provided on the lower peripheral wall surface of the gas introduction pipe 103. Spouted into the liquid. As shown in FIG. 5, the gas introduction pipe 103 in this case has a gas ejection hole 104 disposed on the lower peripheral wall surface thereof. The flue gas ejected into the slurry liquid of the calcium compound in the liquid tank comes into contact with the slurry liquid, and SO ₂ contained in the flue gas is absorbed into the liquid, and at the same time, the air introduction pipe 106 at the lower part of the liquid tank. It is oxidized by oxygen in the air introduced into the liquid from the liquid and reacts with calcium compounds to become CaSO ₄ · 2H ₂ O (gypsum). Reference numeral 112 denotes a gas-liquid separator that captures the liquid entrained by the gas, 105 denotes a stirring blade, and 108 denotes a gypsum slurry extraction pipe.
The flue gas desulfurization apparatus shown in FIG. 4 is actually a very large apparatus, the liquid tank 102 has an inner diameter of 10 m or more, and the number of gas introduction pipes 103 is 1,000 or more. It is a large number.
[0004]
One problem with such an exhaust gas treatment device is that if the amount of gas treatment in a given device is increased in order to reduce the size of the device, there is a limit to the total opening area of the gas ejection holes arranged in the gas introduction pipe. The gas pressure loss increases rapidly. The flow rate of the gas introduced into the liquid through the gas introduction pipe depends on the total opening area of the gas ejection hole, and the amount increases as the total opening area of the gas ejection hole increases, and the gas throughput per unit time Can be increased. However, in this case, since a large amount of gas is ejected from the gas ejection hole into the liquid, this may cause the liquid level to become unstable depending on the conditions and increase the fluctuation range of the liquid level. It may cause deterioration of gas-liquid contact efficiency.
[0005]
[Problems to be solved by the invention]
The present invention provides an exhaust gas treatment apparatus having a structure in which a large number of gas introduction pipes having a plurality of gas ejection holes on a lower peripheral wall surface are suspended in an absorption liquid, while having an increased total area of gas ejection holes. It is an object of the present invention to provide an apparatus that has a small fluctuation range of the liquid level in the tank and that is remarkably excellent in gas processing performance.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.
That is, according to the present invention, there is a structure in which the exhaust gas is introduced and dispersed in the absorbing liquid accommodated in the liquid tank through a large number of gas introduction pipes having a lower end opening and gas ejection holes in the lower peripheral wall surface. In the exhaust gas treatment apparatus, the area ratio between the lower end opening of the gas introduction pipe and the gas ejection hole is 1: 0.1 to 2, and the distance between the lower end of the gas introduction pipe and the lowest part of the gas ejection hole is the gas introduction pipe The gas ejection holes having a diameter of 1 to 8 times the inner diameter of the gas and having a diameter of 10 to 30 mm are arranged in a plurality of stages on the peripheral wall surface of the gas introduction pipe, and the number of gas ejection holes arranged and the gas ejection The relationship with the hole diameter is
2 ≦ n ≦ 80 / D
(Where n indicates the number of gas ejection holes and D indicates the diameter of the gas ejection holes)
An exhaust gas treatment apparatus characterized by satisfying the above is provided.
[0007]
Next, the present invention will be described with reference to the drawings.
FIG. 1 shows an explanatory state diagram when exhaust gas is ejected from an ejection hole of a gas introduction pipe into the absorption liquid through a gas introduction pipe suspended in the absorption liquid. In this figure, 1 is a gas introduction pipe, 2 (1) and 2 (2) are gas ejection holes, 3 is a floss layer, 4 is a top surface of the floss layer, 5 is an absorbing liquid surface in the gas introduction pipe, and 6 is a gas introduction pipe. The lower end of is shown.
The exhaust gas flows downward in the gas introduction pipe 1 and is ejected into the absorbing liquid from the gas ejection holes 2 (1) and 2 (2) disposed on the lower peripheral wall surface of the gas introduction pipe 1. The exhaust gas ejected into the absorbing liquid from the gas ejection holes 2 (1) and 2 (2) rises as fine bubbles, and a froth layer 3 made of a gas-liquid mixture is formed above the gas ejection holes. The fine bubbles of the exhaust gas come into contact with the absorption liquid while moving upward in the froth layer, and the pollutants in the exhaust gas react with the absorption liquid and are removed.
[0008]
When the exhaust gas and the absorbing liquid are brought into contact with each other as described above, the amount of exhaust gas per unit time is increased without increasing the internal pressure of the gas introduction pipe 1, thereby reducing the size of the apparatus. There is a need to increase the diameter of the injection hole of the introduction pipe to introduce and disperse a large amount of gas in the absorbing liquid. According to the study of the present inventors, as shown in FIG. 5, when increasing the gas ejection amount by increasing the diameter of the gas ejection hole in the conventional gas introduction pipe arranged in a row in the peripheral wall surface, Although the amount of gas ejection increases, it has been found that when the diameter of the gas ejection hole exceeds 40 mm, the fluctuation range of the absorbing liquid surface becomes remarkable and the gas-liquid contact efficiency is greatly reduced.
FIG. 2 shows the relationship between the gas superficial velocity (m / sec) and the diameter of the gas injection hole when exhaust gas is injected into the absorption liquid as described above, and the fluctuation range of the absorption liquid surface and the diameter of the gas injection hole. Shows the relationship. In this case, the gas superficial velocity indicates the gas superficial velocity when the exhaust gas ejected from the gas introduction pipe 1 passes through the froth layer 3 and moves upward. The distance between the lowest level and the highest level of the liquid level when the absorbing liquid level 5 fluctuates up and down is shown.
As can be seen from FIG. 2, in the case of the ejection holes arranged in a horizontal row, it is difficult to significantly increase the gas flow rate due to the restriction of the diameter of the ejection holes.
[0009]
Accordingly, the present inventors have examined the arrangement of the gas ejection holes in a plurality of rows, and as a result, found that the result shown in FIG. 3 is obtained.
That is, as can be seen from FIG. 3, the gas superficial velocity increases as the number of ejection holes (diameter: 10 mm) increases, but when the number of ejection holes exceeds 8, the fluctuation range of the liquid level increases. The liquid level fluctuation range becomes large when it becomes large and becomes 10 steps or more.
[0010]
The relationship shown in FIG. 3 is obtained under certain conditions. In the present invention, the following conditions must be satisfied.
(1) The diameter D of the ejection hole is in the range of 10 to 30 mm, preferably 15 to 25 mm.
(2) The diameter R of the gas introduction pipe is 50 to 300 mm.
(3) The area ratio of the lower end opening area of the gas introduction pipe (the cross-sectional area of the gas introduction pipe) and the gas ejection hole area is 1: 0.2-2.
(4) The distance L (see FIG. 1) from the lower end of the gas introduction pipe to the lowest position of the lowermost ejection hole is 1 to 8 times the inner diameter R of the gas introduction pipe.
(5) The relationship between the diameter D of the gas ejection holes and the number n of the arrangement stages of the gas ejection holes satisfies the following formula.
2 ≦ n ≦ 80 / D
(In the formula, n represents the number of gas ejection holes arranged, and D represents the diameter (mm) of the gas ejection holes)
[0011]
【The invention's effect】
The exhaust gas treatment apparatus of the present invention increases the amount of gas introduction and dispersion into the absorption liquid by increasing only the number of arrangement stages of the gas ejection holes under a certain condition without significantly increasing the internal pressure of the gas introduction pipe. The gas throughput per unit time of the apparatus can be improved. Therefore, when processing a certain amount of gas, the apparatus of the present invention can be greatly reduced in size as compared with the conventional apparatus.
The exhaust gas treatment device of the present invention is used as an exhaust gas treatment device with various gas-liquid contacts, for example, flue gas desulfurization that makes contact between an exhaust gas containing sulfurous acid gas and an absorbing liquid made of an alkaline liquid such as a calcium carbonate slurry liquid. The present invention is preferably applied as a device, a decarbonation gas device that makes contact between an exhaust gas containing carbon dioxide gas and an absorbing liquid made of an alkaline liquid, or the like. In particular, the apparatus of the present invention can be advantageously used as a large flue gas desulfurization apparatus having a liquid tank diameter of 10 m or more, particularly 20 m or more.
[Brief description of the drawings]
FIG. 1 shows an explanatory state diagram when exhaust gas is ejected from its gas ejection hole into an absorption liquid through a gas introduction pipe suspended in the absorption liquid.
FIG. 2 shows the relationship between the gas superficial velocity and the diameter of the gas ejection hole, and the relationship between the fluctuation width of the absorbing liquid surface and the diameter of the gas ejection hole.
FIG. 3 shows the relationship between the gas superficial velocity and the number of arrangement stages of gas ejection holes, and the relationship between the fluctuation range of the absorbing liquid level and the number of arrangement stages of gas ejection holes.
FIG. 4 is a schematic view of a conventional exhaust gas treatment device used as a non-smoke desulfurization device.
FIG. 5 shows a structure explanatory diagram of a gas introduction pipe.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,103 Gas introduction pipe 2 (1), 2 (2), 104 Gas ejection hole 3 Floss layer 4 Floss layer upper surface 101 Gas conduit 102 Liquid tank 105 Stirring blade 106 Air introduction pipe 108 Gypsum slurry extraction pipe

Claims

In an exhaust gas treatment apparatus having a structure in which exhaust gas is introduced and dispersed through a large number of gas introduction pipes having a lower end opening and gas ejection holes in a lower peripheral wall surface in an absorbing liquid accommodated in a liquid tank, the gas introduction The area ratio between the lower end opening of the pipe and the gas ejection hole is 1: 0.1 to 2, and the distance between the lower end of the gas introduction pipe and the lowest part of the gas ejection hole is 1 to 8 times the inner diameter of the gas introduction pipe The gas ejection holes having a diameter of 10 to 30 mm are disposed in the lateral direction in a plurality of stages on the peripheral wall surface of the gas introduction pipe, and the relationship between the number of gas ejection holes and the gas ejection hole diameter is expressed by the formula 2. An exhaust gas treatment apparatus satisfying 2 ≦ n ≦ 80 / D (where n represents the number of gas ejection holes and D represents the diameter of the gas ejection holes).